/* Id */

/*
 * Copyright (c) 1988-1997 Sam Leffler
 * Copyright (c) 1991-1997 Silicon Graphics, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software and 
 * its documentation for any purpose is hereby granted without fee, provided
 * that (i) the above copyright notices and this permission notice appear in
 * all copies of the software and related documentation, and (ii) the names of
 * Sam Leffler and Silicon Graphics may not be used in any advertising or
 * publicity relating to the software without the specific, prior written
 * permission of Sam Leffler and Silicon Graphics.
 * 
 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, 
 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY 
 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.  
 * 
 * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF 
 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE 
 * OF THIS SOFTWARE.
 */

#include "tiffiop.h"
#ifdef PACKBITS_SUPPORT
/*
 * TIFF Library.
 *
 * PackBits Compression Algorithm Support
 */
#include <stdio.h>

static int
PackBitsPreEncode(TIFF* tif, tsample_t s)
{
        (void) s;

        if (!(tif->tif_data = (tidata_t)_TIFFmalloc(sizeof(tsize_t))))
                return (0);
        /*
         * Calculate the scanline/tile-width size in bytes.
         */
        if (isTiled(tif))
                *(tsize_t*)tif->tif_data = TIFFTileRowSize(tif);
        else
                *(tsize_t*)tif->tif_data = TIFFScanlineSize(tif);
        return (1);
}

static int
PackBitsPostEncode(TIFF* tif)
{
        if (tif->tif_data)
            _TIFFfree(tif->tif_data);
        return (1);
}

/*
 * NB: tidata is the type representing *(tidata_t);
 *     if tidata_t is made signed then this type must
 *     be adjusted accordingly.
 */
typedef unsigned char tidata;

/*
 * Encode a run of pixels.
 */
static int
PackBitsEncode(TIFF* tif, tidata_t buf, tsize_t cc, tsample_t s)
{
        unsigned char* bp = (unsigned char*) buf;
        tidata_t op, ep, lastliteral;
        long n, slop;
        int b;
        enum { BASE, LITERAL, RUN, LITERAL_RUN } state;

        (void) s;
        op = tif->tif_rawcp;
        ep = tif->tif_rawdata + tif->tif_rawdatasize;
        state = BASE;
        lastliteral = 0;
        while (cc > 0) {
                /*
                 * Find the longest string of identical bytes.
                 */
                b = *bp++, cc--, n = 1;
                for (; cc > 0 && b == *bp; cc--, bp++)
                        n++;
        again:
                if (op + 2 >= ep) {             /* insure space for new data */
                        /*
                         * Be careful about writing the last
                         * literal.  Must write up to that point
                         * and then copy the remainder to the
                         * front of the buffer.
                         */
                        if (state == LITERAL || state == LITERAL_RUN) {
                                slop = op - lastliteral;
                                tif->tif_rawcc += lastliteral - tif->tif_rawcp;
                                if (!TIFFFlushData1(tif))
                                        return (-1);
                                op = tif->tif_rawcp;
                                while (slop-- > 0)
                                        *op++ = *lastliteral++;
                                lastliteral = tif->tif_rawcp;
                        } else {
                                tif->tif_rawcc += op - tif->tif_rawcp;
                                if (!TIFFFlushData1(tif))
                                        return (-1);
                                op = tif->tif_rawcp;
                        }
                }
                switch (state) {
                case BASE:              /* initial state, set run/literal */
                        if (n > 1) {
                                state = RUN;
                                if (n > 128) {
                                        *op++ = (tidata) -127;
                                        *op++ = (tidataval_t) b;
                                        n -= 128;
                                        goto again;
                                }
                                *op++ = (tidataval_t)(-(n-1));
                                *op++ = (tidataval_t) b;
                        } else {
                                lastliteral = op;
                                *op++ = 0;
                                *op++ = (tidataval_t) b;
                                state = LITERAL;
                        }
                        break;
                case LITERAL:           /* last object was literal string */
                        if (n > 1) {
                                state = LITERAL_RUN;
                                if (n > 128) {
                                        *op++ = (tidata) -127;
                                        *op++ = (tidataval_t) b;
                                        n -= 128;
                                        goto again;
                                }
                                *op++ = (tidataval_t)(-(n-1));  /* encode run */
                                *op++ = (tidataval_t) b;
                        } else {                        /* extend literal */
                                if (++(*lastliteral) == 127)
                                        state = BASE;
                                *op++ = (tidataval_t) b;
                        }
                        break;
                case RUN:               /* last object was run */
                        if (n > 1) {
                                if (n > 128) {
                                        *op++ = (tidata) -127;
                                        *op++ = (tidataval_t) b;
                                        n -= 128;
                                        goto again;
                                }
                                *op++ = (tidataval_t)(-(n-1));
                                *op++ = (tidataval_t) b;
                        } else {
                                lastliteral = op;
                                *op++ = 0;
                                *op++ = (tidataval_t) b;
                                state = LITERAL;
                        }
                        break;
                case LITERAL_RUN:       /* literal followed by a run */
                        /*
                         * Check to see if previous run should
                         * be converted to a literal, in which
                         * case we convert literal-run-literal
                         * to a single literal.
                         */
                        if (n == 1 && op[-2] == (tidata) -1 &&
                            *lastliteral < 126) {
                                state = (((*lastliteral) += 2) == 127 ?
                                    BASE : LITERAL);
                                op[-2] = op[-1];        /* replicate */
                        } else
                                state = RUN;
                        goto again;
                }
        }
        tif->tif_rawcc += op - tif->tif_rawcp;
        tif->tif_rawcp = op;
        return (1);
}

/*
 * Encode a rectangular chunk of pixels.  We break it up
 * into row-sized pieces to insure that encoded runs do
 * not span rows.  Otherwise, there can be problems with
 * the decoder if data is read, for example, by scanlines
 * when it was encoded by strips.
 */
static int
PackBitsEncodeChunk(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
{
        tsize_t rowsize = *(tsize_t*)tif->tif_data;

        while ((long)cc > 0) {
                int     chunk = rowsize;
                
                if( cc < chunk )
                    chunk = cc;

                if (PackBitsEncode(tif, bp, chunk, s) < 0)
                    return (-1);
                bp += chunk;
                cc -= chunk;
        }
        return (1);
}

static int
PackBitsDecode(TIFF* tif, tidata_t op, tsize_t occ, tsample_t s)
{
        char *bp;
        tsize_t cc;
        long n;
        int b;

        (void) s;
        bp = (char*) tif->tif_rawcp;
        cc = tif->tif_rawcc;
        while (cc > 0 && (long)occ > 0) {
                n = (long) *bp++, cc--;
                /*
                 * Watch out for compilers that
                 * don't sign extend chars...
                 */
                if (n >= 128)
                        n -= 256;
                if (n < 0) {            /* replicate next byte -n+1 times */
                        if (n == -128)  /* nop */
                                continue;
                        n = -n + 1;
                        if( occ < n )
                        {
                                                        TIFFWarningExt(tif->tif_clientdata, tif->tif_name,
                                        "PackBitsDecode: discarding %d bytes "
                                        "to avoid buffer overrun",
                                        n - occ);
                            n = occ;
                        }
                        occ -= n;
                        b = *bp++, cc--;
                        while (n-- > 0)
                                *op++ = (tidataval_t) b;
                } else {                /* copy next n+1 bytes literally */
                        if (occ < n + 1)
                        {
                            TIFFWarningExt(tif->tif_clientdata, tif->tif_name,
                                        "PackBitsDecode: discarding %d bytes "
                                        "to avoid buffer overrun",
                                        n - occ + 1);
                            n = occ - 1;
                        }
                        _TIFFmemcpy(op, bp, ++n);
                        op += n; occ -= n;
                        bp += n; cc -= n;
                }
        }
        tif->tif_rawcp = (tidata_t) bp;
        tif->tif_rawcc = cc;
        if (occ > 0) {
                TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
                    "PackBitsDecode: Not enough data for scanline %ld",
                    (long) tif->tif_row);
                return (0);
        }
        return (1);
}

int
TIFFInitPackBits(TIFF* tif, int scheme)
{
        (void) scheme;
        tif->tif_decoderow = PackBitsDecode;
        tif->tif_decodestrip = PackBitsDecode;
        tif->tif_decodetile = PackBitsDecode;
        tif->tif_preencode = PackBitsPreEncode;
        tif->tif_postencode = PackBitsPostEncode;
        tif->tif_encoderow = PackBitsEncode;
        tif->tif_encodestrip = PackBitsEncodeChunk;
        tif->tif_encodetile = PackBitsEncodeChunk;
        return (1);
}
#endif /* PACKBITS_SUPPORT */

/* vim: set ts=8 sts=8 sw=8 noet: */
